convert Value::*Value() function to return Maybe results

include/v8.h

Index: include/v8.h
diff --git a/include/v8.h b/include/v8.h
index a6b1d4d8b2e097d8bb0a54df346f035881e2b57a..a9cdc261921dbd42c2d432024b1917310ef92990 100644
--- a/include/v8.h
+++ b/include/v8.h
@@ -977,12 +977,32 @@ class V8_EXPORT EscapableHandleScope : public HandleScope {
  * A simple Maybe type, representing an object which may or may not have a
  * value.
  */
-template<class T>
+template <class T>
+// TODO(dcarney): make class.
 struct Maybe {
   Maybe() : has_value(false) {}
   explicit Maybe(T t) : has_value(true), value(t) {}

[Sven Panne, 2015/02/27 12:18:02]

While we're here: Make this a "const T& t", the current signature is
embarrassing.

+  // TODO(dcarney): remove this constructor, it makes no sense.
   Maybe(bool has, T t) : has_value(has), value(t) {}
 
+  bool HasValue() { return value; }

[Sven Panne, 2015/02/27 12:18:03]

This should return has_value, I guess...

+
+  V8_WARN_UNUSED_RESULT V8_INLINE bool ToValue(T* out) const {
+    if (has_value) {

[Sven Panne, 2015/02/27 12:18:02]

Test is wrong, safer and more obvious way:

  *out = has_value ? value : T();
  return has_value;

+      *out = T();
+      return false;
+    } else {
+      *out = this->value;
+      return true;
+    }
+  }
+
+  V8_INLINE T ToValueChecked() {
+    // TODO(dcarney): add DCHECK.
+    return value;
+  }
+
+  // TODO(dcarney): make private.
   bool has_value;
   T value;
 };
@@ -1921,6 +1941,13 @@ class V8_EXPORT Value : public Data {
    */
   Local<Uint32> ToArrayIndex() const;
 
+  Maybe<bool> BooleanValue(Local<Context> context) const;
+  Maybe<double> NumberValue(Local<Context> context) const;
+  Maybe<int64_t> IntegerValue(Local<Context> context) const;
+  Maybe<uint32_t> Uint32Value(Local<Context> context) const;
+  Maybe<int32_t> Int32Value(Local<Context> context) const;
+
+  // TODO(dcarney): deprecate all these.
   bool BooleanValue() const;
   double NumberValue() const;
   int64_t IntegerValue() const;